Final answer:
The submaximal fitness test in question assesses cardiovascular fitness by measuring the heart rate after stepping at a certain cadence. For a heart rate of 150 bpm during strenuous exercise, the time per beat is 0.4 seconds. This is significant in understanding the physiological changes in heart function during exercise.
Step-by-step explanation:
The submaximal test that involves stepping for 3 minutes at a cadence of 22 steps per minute and measuring heart rate for 15 seconds afterwards while the subject stands is used to assess cardiovascular fitness. During strenuous exercise, an increase in heart rate (HR) is a normal response. For example, for a person who has a heart rate of 150 beats per minute during such exercise, the time per beat is calculated by taking 60 seconds (since there are 60 seconds in a minute) and dividing it by the number of beats per minute (150 bpm), yielding a time of 0.4 seconds per beat. This value is crucial for exercise physiology and understanding the cardiovascular response to exercise. Especially in cardiovascular athletes, the heart's stroke volume (SV) and cardiac output (CO) can significantly increase, affecting the heart rate and power output during peak performance.